summary of observation for Causeway Link Cross border Bus services:
from 1st link,
board at Sultan Iskandar CIQ, bus dunno where you want to go, so only charge you rm 2.6
board at Woodland checkpoint, each bus knows where you want to go, so deduct the the amount difference from if you pay upfront with cash (rm2.2 to queen st, rm0 to kranji, rm2 to newton circus)
from 2nd link
every bus knows you want to go CIQ, so charge max fare according to each bus number (rm4.5 from gelang patah/hotel ramada/hotel jen, rm6 from BI/perling/sutera, rm7 from tuta, rm8 from pontian). after cross border, they don't care where you want to go and no extra charge.
todo:
try to board from perling and alight at BI and tap out
try to board from BI and alight few bus stops after that and tap out